1. Field of the Invention
This invention resides in the fields of quality control for clinical laboratory test procedures and instrumentation, and of human Factor XIII protein and its uses.
2. Description of the Prior Art
The medical community, including practicing physicians, researchers, and clinicians of all types rely on the clinical laboratory for analytical testing of biological samples as part of routine physical examinations, and in diagnosing disease and monitoring patient progress and disease conditions, as well as similar functions and services. Among the most common biological samples that are analyzed by these laboratories are serum and plasma, although other fluids such as urine and cerebrospinal fluid are often used as well. Many analyses are performed by automated instrumentation, and in some cases large numbers of samples are analyzed simultaneously. Whether the tests are performed in this manner or on an individual basis by a laboratory technician, there are numerous sources of error that can produce spurious results.
The error that arises falls within two general classes—(1) spurious test results due to lapses in standard operating procedures and instrument malfunctions, and (2) analytic error. Some of the most common errors of the first class are those due to inaccurate mathematical correction for specimen dilution, misinterpretation of instrument codes, and instrument sampling errors such as bubbles in sample wells or transfer tubing or other malfunctions that result in samples whose volumes are less than standard. Of the second class, the most common type of error is that caused by calibration drift. This invention addresses errors of the first class. In proficiency testing, these errors have been shown to account for 300 false test results per one million assays. A review of the causes of laboratory errors is reported by Jenny, R. W., et al., “Causes of Unsatisfactory Performance in Proficiency Testing,” Clin. Chem. 46(1): 89–99 (2000), who found that inaccurate dilution corrections accounted for 21% of spurious test results in proficiency testing, and missampling in a particular automated instrument such as might be caused by air bubbles or sample clotting occurred 0.016% of the time, during use of the instrument in testing for samples from the general population. A further source of error is the use of an incorrect sample type, such as urine, cerebrospinal fluid, or other bodily fluids instead of serum, or in coagulation studies the failure to differentiate between serum and plasma.